The Neoproterozoic Purcell Sill is a stark, obvious black stripe in the strata of Glacier National Park. Here it is emerging from behind “The Salamander” glacier, above Grinnell Glacier Cirque:

Zooming in, you can see the “baked” (bleached) zones above and below this concordant intrusion.

But this time, during my visit to this special place, I noticed a discordant offshoot from the main sill:

See it? Up there at the head of that valley:

Zooming in further, you can see four people standing on the contact metamorphosed zone on the left side of this dike:

I went and searched for it in Google Maps, and found it quite easily emerging from that icy valley;

How this escaped my notice during my previous trips to this site, I’ll never know. I was glad to find something new there, though.